Reinforced concrete piers are widely used in bridges at present. However, such kind of pier is very easy to be damaged under earthquake, which may lead to severe bridge accidents. Flexural failure and shear failure are two major damage types of reinforced concrete piers under earthquake. The flexural failure is caused by the insufficient flexural stiffness of the pier, and mainly happens in medium and high piers. The shear failure is caused by insufficient shear stiffness of the pier, and mainly happens in medium and low piers. Compared with the ductile flexural failure, the shear failure is a kind of brittle failure and may sometimes lead to more severe bridge accidents. Therefore, a high reinforcement ratio should be avoided for the medium and low reinforced concrete piers, and the shear stiffness of the reinforced concrete piers shall be guaranteed to be larger than the flexural stiffness.
Presently, in order to improve the aseismic performance of the pier, for rigid piers, the resistance to earthquakes is mainly improved by increasing the section area, increasing the reinforcement ratio, or using a reinforced-concrete composite structure, etc. For flexible piers, the shear bearing capacity and the shear deformation capacity thereof are mainly improved by optimizing the reinforcement ratio and the form of cross-section thereof. Since steel has a higher strength and a better ductility than concrete, some steel piers and concrete-filled steel tube composite piers are adopted in engineering. However, the cost these piers is relatively, bringing some limitations to the practical application.